Electric switch gear



' Y 1938. c. THUMIM ET AL 6 ELECTRIC SWITCHGEAR Filed Oct. 12, 1955 2 Sheets-Sheet 1 Car! Thumim, Harold E. Strang,

ThemAttorne g.

July 5, 1938. c. THUMIM ET AL ELECTRIb' SWITCH GEAR Filed Oct. 12, 1955 2 Sheets-Sheet 2 Inventors Carl Thumim, HeLrold'EflStT" b WM 7 5 r9 TheirAttOrne g.

Patented July 5, 1938 UNITE STATES PATET OFFIQE ELECTRIC S HITCH GEAR Application October 12, 1935, Serial No. 44,740

4 Claims.

Our invention relates to electric switchgear, more particularly to high tension circuit breakers of the liquid-break or oil insulated type designed for comparatively high operating speed.

" In prior designs of oil circuit breakers for high tension power circuits at commercial frequencies, the operating mechanism was generally either located beneath or adjacent the lower part of the breaker casing in which case it was connected to "the movable contact structure of the breaker by means of cranks and linkages through the top of the breaker casing, or the entire mechanism was mounted above the breaker. In the latter case the mechanism is not readily accessible and the overall height of the breaker is often greatly increased, thus presenting serious installation problems. These arrangements were in many cases not only complicated, awkward and expensive, but in the case of added friction of linkage structure the power output of the operating mechanism had to be increased accordingly. Furthermore, where high opening speed of the breaker Was required the inertia of complicated linkage structure was a serious disadvantage, particularly where acceleration of the mechanism within ,a cycle or two of a Gil-cycle circuit was re quired.

The principal object of our invention is the provison of means for increasing the efficiency and. EO speed of a high tension circuit breaker of the aforesaid type and simplifying the operating mechanism and the insulation thereof.

Our invention will be more fully set forth in the following description referring to the accomgs panying drawings, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification. Referring to the drawings, Fig. 1 is an eleva- 4(')*"tional View, partly in section, of a high tension circuit breaker to which our invention is applied, and Fig. 2 is an enlarged sectional view of a portion of the structure shown by Fig. 1 illustrating our invention.

45 Referring to Fig. 1, the high tension circuit breaker, illustrated by way of example, comprises a pair of horizontally arranged circuit breaker units l and 2 which are supported by vertical insulating pillars, 3, 4 and 5 mounted on structural framework 6. The framework 6 likewise supports suitable operating mechanism 1 for the circuit breaker, which may be of any suitable type, such as the well known spring-operated type for example. The operating mechanism is connected to the movable contact structure in the breaker units l and 2 by means of an actuating rod 8 which extends vertically through the central insulating pillar 4 and connects, in any suitable manner, at the junction 9 with the movable contact structure in the opposite units.

A detailed description of the circuit breaker itself is unnecessary for a clear understanding of the present invention, other than to point out that the breaker or interrupting units l and 2 contain a suitable insulating and are extinguishing liquid, such as oil, within which the relatively movable breaker contacts are immersed. By way of further description, but without limitation thereto, the circuit breaker may be of the character disclosed and claimedin a copending application Serial No. 25,267, filed June 6, 1935, by David C. Prince for Electric circuit breakers and assigned to the same assignee as the present invention.

The operation of the circuit breaker is eiTected by reciprocal movement of the rod 8 which is connected at its lower end, at Hi to a pivoted mechanism arm Hi by links I I.

In high voltage circuit breakers of the character in question, insulation of the operating mechanism with respect to the high voltages encountered is an important consideration, and in the present instance the operating rod 8, which extends centrally of the insulating pillar 4, is oil insulated. The conventional type of seal, such as a stuifing box, has proved inadequate for preventing loss of a liquid having a low surface tension, such as oil. In accordance with our invention the rod 8 is immersed in oil within the pillar 4 and is provided with a low friction liquid seal at I l2 which is effective not only to maintain the insulating oil within the pillar but which also offers inappreciable resistance to operation of the rod 8 which is directly connected to the operating mechanism at 7.

Referring more particularly to Fig. 2, the insusecured to the plate 6, such as by a split wedge ring at [8. The insulating tube ll extends upwardly within the pillar and forms the casing for the insulating oil [9 within which the operating rod 8 is immersed.

The sealing arrangement between the oil casing and the operating arm ID of the mechanism comprises a low friction oil-mercury seal wherein a column of mercury is balanced by the head of oil 19 in the pillar 4. To this end, the sleeve [5 is suitably joined to a depending cylinder 20 having a reduced portion 2| which is closed in part by a flange 22 at its lower end. The inner periphery of the flange is united to a sleeve 23 which extends concentrically within the cylinder 2| so as to form an annular pocket, which is closed at its lower end, in the cylinder 2|. The operating rod 8, which in the present instance is composed of a suitable, strong insulating material, as laminated wood impregnated with a synthetic resin, is provided with a reduced section 8' which extends centrally of the fixed sleeve 23. At a point above the upper end of the sleeve 23 there is secured to the operating rod 8, at 24, a sleeve 25 which is closed at its upper end and arranged in telescopic relation with respect to the fixed sleeves 2| and 23 so as to form an inverted cup within the above described annular space.

For the purpose of maintaining the oil within the pillar 4, a body of mercury 26 of suitable volume is placed within said annular space prior to the addition of the oil l9. With the inverted cup 25 in the annular pocket as shown and spaced from the bottom thereof there is formed an annular U-tube, both branches of which contain an equal amount of mercury 26.

Accordingly, when the oil I9 is added the mercury in the inner branch is raised by the head of oil, as illustrated, to balance the oil. For the purpose of preventing splashing and accidental loss of mercury 26, a suitable gasket or packing washer may be provided at 21 between the upper end of the sleeve 23 and the movable cup 25.

This arrangement, therefore, permits limited reciprocal movement of the inverted cup 25, and hence rod 8, in the cylinder 2| without loss of oil, and it will be apparent that there is inappreciable friction involved since the inverted cup 25 moves entirely with respect to two fluids. The oil If! in the present instance is not subjected to the pressures generated during arc interruptions within the units I and 2. However, the operating rod 8 in certain cases may, if desired, extend directly from beneath into the circuit breaker casing proper in the manner shown in Fig. 2 through a low-friction liquid seal of the character above described. In such cases, the gasket 21 serves to prevent loss of mercury due to a momentary sudden increase in pressure in the oil body during a circuit interruption.

The term oil as used herein is intended to comprehend a suitable arc-extinguishing or insulating liquid. Also the term mercury similarly used is intended to comprehend a suitable sealing liquid having a specific gravity greater than the oil.

It should be understood that our invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. In a high voltage circuit breaker including a casing containing a liquid having a low surface tension such as oil and a circuit breaker operating rod extending from beneath into the liquid within said casing for relative movement with respect thereto, a low friction liquid seal between said casing and rod comprising relatively movable telescopic structure secured to said casing and rod respectively so as to form a U-tube, one branch of which is in communication with said oil, and a body of mercury in said U-tube for balancing the head of said oil whereby relative movement of said rod can be effected at high speed without loss of said oil or mercury.

2. In a high voltage circuit breaker including a casing containing a liquid having a low surface tension such as oil and a circuit breaker operating rod extending from beneath into the oil within said casing for reciprocal movement with respect thereto, a liquid seal between said casing and rod comprising relatively movable telescopic structure secured to said casing and rod respectively so as to form a U-tube, one branch of which is in communication with said oil, a body of mercury in said U-tube for balancing the head of said oil whereby reciprocal movement of said rod can be efiected at high speed without loss of said oil or mercury, and means likewise coacting with said casing and rod for preventing loss of said mercury in case of momentary high pressure in said oil.

3. In a high speed circuit breaker for high tension power circuits including a casing structure containing oil, circuit breaker operating mechanism, and an operating rod structure connected to said mechanism and extending from beneath into the oil within said casing, a liquid seal between said structures comprising a pair of concentric sleeves fixed with respect to one of said structures and forming an annular pocket, a body of mercury in said pocket, and means forming an inverted cup extending into said pocket and carried by the other of said structures so as to form an annular U-tube, one branch of said U-tube being in communication with the oil in said casing so that the head of said oil is balanced by said mercury, said operating rod structure having an extension freely movable centrally of said seal for connection to said operating mechanism, and packing means disposed at the other branch of said U-tube for preventing loss of mercury in case of momentary high pressure in said oil.

4. In a high speed circuit breaker for high tension power circuits including an insulating and supporting pillar, operating mechanism disposed beneath said pillar and connected to a reciprocally movable rod extending vertically through said pillar, and an insulating oil in said pillar in which said rod is immersed, a liquid seal between said pillar and rod comprising relatively movable telescopic means secured respectively to said pillar and said rod forming a U-tube concentrically of said rod at the lower part of said pillar, said U-tube containing a body of mercury and arranged so that one branch thereof is in communication for all positions of said operating rod with the oil within said pillar whereby the head of said oil is balanced by said mercury, said operating rod extending freely through the central part of said U-tube for connection with said operating mechanism, and means for sub stantially precluding loss of mercury from said U- tube.

CARL THUMIM. HAROLD E. STRANG. 

